safety belt vs constraint

safety belt and constraint both are nouns.

Word	Noun	Adjective	Verb	Adverb
safety belt	Yes	No	No	No
constraint	Yes	No	No	No

As nouns, constraint is a hypernym of safety belt; that is, constraint is a word with a broader meaning than safety belt:

safety belt: belt attaching you to some object as a restraint in order to prevent you from getting hurt
constraint: a device that retards something's motion

Other hypernyms of safety belt include belt, restraint.

safety belt (noun)	constraint (noun)
belt attaching you to some object as a restraint in order to prevent you from getting hurt	the act of constraining; the threat or use of force to control the thoughts or behavior of others
	a device that retards something's motion
	the state of being physically constrained